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Search Results: 1 - 10 of 4551 matches for " fluorescence spectrometry "
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3D Fluorescence Characterization of Synthetic Organic Dyes  [PDF]
Leonard J. Soltzberg, Sandy Lor, Nnennaya Okey-Igwe, Richard Newman
American Journal of Analytical Chemistry (AJAC) , 2012, DOI: 10.4236/ajac.2012.39081
Abstract: The identification of dyes is important in research on museum artefacts as well as in forensic applications. UV-visible absorption spectroscopy cannot unambiguously distinguish dyes with similar hues, while mass spectrometry may fail to distinguish isobaric dyes. The detailed patterns produced by 3D fluorescence spectroscopy appear to be virtually unique, even among dyes that are closely related positional isomers. We report these patterns for 65 dyes from the Schweppe Library of Synthetic Organic Dyes as well as measurements suggesting both the capabilities and limitations of this method.
Chemical Characterization of Auriferous Ores from the Brazilian State of Paraiba  [PDF]
Marcelo Rodrigues do Nascimento, Artur M. G. Louren?o
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2015, DOI: 10.4236/jmmce.2015.31002
Abstract: One of the most important problems facing the gold industry is that the placer and free milling gold ores are almost terminating. Hence, the use of refractory ores has been increased during the recent years. In general, gold refractory ores occurs in various types of deposits associated with a range of minerals. Among the refractory ores, the sulfide type is the most common. The methodology employed in the mining process depends on the mode of occurrence of the ore and on the particle size, shape and degree of purity of the auriferous species. We have undertaken a mineralogical investigation of a representative sample of a complex gold mining ore collected in the municipality of Princesa Isabel, Paraiba, Brazil, using X-ray fluorescence spectrometry, X-ray diffractometry, infrared spectroscopy, inductively coupled plasma-atomic emission spectrometry and the Fire Assay. The results showed that the arsenic content of the ore was closely related to the gold content, and that the occurrence of “invisible gold” was associated primarily with pyrite and secondarily with arsenopyrite. The sulfur content of the ore was directly related to its refractoriness. It is concluded that gold mineralization in the study area is mainly of the gold-quartz-sulfide veins (lode gold), while the gold found in the mini-fractures of the deposits is probably associated with the hydrothermal processes that occurred in the region.
Total integration method of three-dimensional fluorescence spectrometry
Yan Yuan,Xu Jingou,Chen Guozhen
Chinese Science Bulletin , 1997, DOI: 10.1007/BF02882927
Abstract:
Studies on the Inclusion Behavior of Amphiphilic p-Sulfonatocalix[4]arene with Ascorbic Acid by Spectrofluorometric Titrations  [PDF]
Yunyou Zhou, Xueping Ding, Xiaoli Fang, Tao Li, Dongbao Tang, Qin Lu
Optics and Photonics Journal (OPJ) , 2011, DOI: 10.4236/opj.2011.12009
Abstract: The aqueous solution of tetrabutyl ether derivatives of p-sulfonatocalix[4]arene (SC4Bu) and ascorbic acid (AA) complex has been studied based on fluorescence and 1H NMR spectroscopic results. It was found that the fluorescence intensity of SC4Bu quenched regularly upon the addition of AA. A 1:1 stoichiometry for the complexation was established and was verified by Job’s plot. The temperature-dependent inclusion constants were calculated, form which Δ H and ΔS values were calculated. Meanwhile the proposed interaction mechanism of the inclusion complex was discussed based on 1H NMR results. The various factors (ionic strength, and surfactants) effecting the inclusion process were examined in detail.
A terapia fotodinamica com ácido 5-aminolevulínico como modalidade de tratamento para neoplasias cutaneas n?o-melanoma
Felício, Lília Bernardini Antunes de;Ferreira, Juliana;Bentley, Maria Vitória Badra;Bagnato, Vanderlei Salvador;Tedesco, Cláudio Antonio;Souza, Cacilda da Silva;
Anais Brasileiros de Dermatologia , 2008, DOI: 10.1590/S0365-05962008000400004
Abstract: background: photodynamic therapy is based on the association of a light source and photosensitizer in order to selectively destroy cells. objective: to evaluate the short and long-term effects, clinical response, and cosmetic outcome of the photodynamic therapy with 5-aminolaevulinic acid for non-melanoma skin cancer. methods: tthirty-four non-melanoma skin cancer - 19 bowen?s diseases and 15 basal cell carcinomas, were submitted to a single 6-hour topical and occlusive application of 20% 5-aminolaevulinic acid, and were later exposed to 630 nm diode laser single session. results: burning sensation during the session; erythema, edema and erosions in the first 72 hours; healing process after 4 weeks on average and excellent or good cosmetic results were observed. after 3 months, tumor-free rate was 91.2% whereas at 18 months,73.3%, similarly in bowen?s disease (72.2%) and basal cell carcinoma (75%). it was noticed a linear relation between the reduction in complete clinical response frequency and the increase in tumor dimension (p<0.001). conclusion: the 5-aminolaevulinic acid photodynamic therapy showed significant advantages such as minimally invasive for the treatment of multiple lesions in only one session or lesions in poor healing sites with superior esthetical outcome. the clinical and histopathological type/sub-type, the dimension and an appropriate follow-up must be considered to indicate topical 5-aminolaevulinic acid photodynamic therapy for non-melanoma skin cancer.
Quantitative Analysis of FeMo Alloys by X-Ray Fluorescence Spectrometry  [PDF]
Sung-Mo Jung
American Journal of Analytical Chemistry (AJAC) , 2014, DOI: 10.4236/ajac.2014.512085
Abstract: A quantitative analysis method of molybdenum in FeMo alloys by X-ray spectrometry using borate fusion technique was compared with that with pressed pellet. The complete pre-oxidation of FeMo alloys for the preparation of homogeneous fused discs was achieved by employing an automated fusion machine equipped with specially designed O2-blowing nozzles, which used lithium tetra-borate as flux with the addition of lithium nitrate (LiNO3) as oxidizer. The calibration curves of Mo and Fe were used in the quantitative analysis of standard materials and unknown plant samples with satisfactory accuracy and precision, utilizing the corrections of the matrix effects and line overlap. It was confirmed that the newly proposed method of preparing fused glass discs of FeMo alloys can replace the conventional wet chemical analyses requiring the labor intensive and time consuming procedure.
X射线荧光光谱法测定铝土矿中组分不确定度评估
Uncertainty Evaluation for the Determination of Components in Bauxite Samples by X-Ray Fluorescence Spectrometry
 [PDF]

袁建, 夏晨光, 刘香英, 刘高辉
Advances in Analytical Chemistry (AAC) , 2016, DOI: 10.12677/AAC.2016.62005
Abstract:
本文以X射线荧光光谱法测定铝土矿中Al2O3为例,详细论述该方法在分析过程可能产生的不确定来源,并对各分量不确定进行了评定。通过研究可知,X射线荧光光谱法测定铝土矿中Al2O3时不确定来源有许多,主要有测量不确定度引入的不确定度、标准样品引入的不确定度、称量误差导致的不确定度等方面,本文通过计算出各分量的不确定度,对各个分量不确定度进行定量分析,最后合成得到测量结果的扩展不确定度。
The study discussed the source of uncertainty about measuring the Al2O3 of bauxite by X-ray Fluo-rescence Spectrometry in detail; moreover, we assessed the uncertainty of all components possibly. According to the research we could know there were several reasons that caused the uncertainty about measuring the Al2O3 by X-ray Fluorescence Spectrometry, such as the method of measurement, standard reference materials, weighing error, etc. The uncertainty of each compo-nent was calculated and analyzed quantitatively; the extended uncertainty of measurement results was obtained from synthesis of each uncertainty source.
Binding of Bezafibrate to Human Serum Albumin: Insight into the Non-Covalent Interaction of an Emerging Contaminant with Biomacromolecules
Yajie Qian,Xuefei Zhou,Jiabin Chen,Yalei Zhang
Molecules , 2012, DOI: 10.3390/molecules17066821
Abstract: In recent years, bezafibrate (BZF) has been frequently detected in environmental media. In order to reveal the toxicity of such an emerging pollutant, its interaction with human serum albumin (HSA) was studied by fluorescence spectrometry, circular dichroism, and equilibrium dialysis. Fluorescence data showed that the fluorescence quenching of HSA by BZF resulted from the formation of HSA-BZF complex. The binding constants were determined to be 3.33 × 103, 2.84 × 103 M?1 at 298 and 309.5 K, respectively. The thermodynamic determination indicated that the hydrophobic and electrostatic interaction were the dominant binding force. The conformational investigation showed that the presence of BZF increased the α-helix content of HSA and induced the slight unfolding of the polypeptides of protein. Finally, the equilibrium dialysis showed that 0.56 mM BZF decreased the binding of vitamin B2 to HSA by 29%.
Determination of inorganic species of Sb and Te in cereals by hydride generation atomic fluorescence spectrometry
Reyes, Mariela N. M;Cervera, Maria L;Guardia, Miguel de la;
Journal of the Brazilian Chemical Society , 2011, DOI: 10.1590/S0103-50532011000200002
Abstract: a non-chromatographic fast, sensitive and easy method has been developed for the determination of sb(iii), sb(v), te(iv) and te(vi) in cereal samples. the procedure is based on ultrasound assisted extraction and determination by hydride generation atomic fluorescence spectrometry (hg afs). preliminary studies were made in order to get the best extraction efficiency using 1 mol l-1 phosphoric acid, 1 mol l-1 nitric acid, aqua regia, 1 mol l-1 sulfuric acid and 6 mol l-1 hydrochloric acid. the extraction with aquaregia showed a clear interconversion of the species during the process, being h2so4 the best extractant with efficiencies greater than 90% from the total content of sb and te quantified previously and without species interconversion. this point was checked by recovery experiments at different spiked levels. the method provided limits of detection values from 0.1 to 0.5 ng g-1 with relative standard deviation values from 5.4 to 9.2% of 10 independent analysis of samples containing few ng g-1 of sb and te species.
Terapia fotodinamica com ftalocianina de zinco tópica: avalia??o da intensidade de fluorescência, absor??o cutanea, altera??es histológicas e imuno-histoquímicas na pele do modelo animal
Tomazini, Marília Vannuchi;Souza, Cacilda da Silva;Garcia, Sérgio Britto;Tedesco, Ant?nio Cláudio;
Anais Brasileiros de Dermatologia , 2007, DOI: 10.1590/S0365-05962007000600006
Abstract: background - phthalocyanines are promising photosensitizers used in photodynamic therapy (pdt). objectives - to evaluate the following parameters: intervals, vehicles and enhancer using topical zinc-phthalocyanine (zn-pc) formulation. to examine macro and micromorphological changes and fas expression induced by topical zn-pc-pdt on murine skin. material and methods - using fluorescence spectrometry, different intervals of topical occlusion employing zn-pc gel or emulsion, with or without monolein 5% were studied. after an 8-hour occlusion of different formulations, the mice were exposed to 670 nm laser, at a 50 j.cm-2 dose. results - fluorescence was slightly higher after 8 hours, and also with emulsion formulation at one-, two- and four-hour occlusion periods. the intensity of edema and erosion were correlated to epidermal necrosis and to fas immunoexpression in skin histological specimens. conclusions - the results show the effects of photodynamic action promoted by the interaction between zn-pc formulation and a 670-nm light source. macro and micromorphological alterations were correlated and more substantial with monolein and zn-pc emulsion, suggesting more marked effects with this formulation. the fas immunoexpression and histological changes suggested that apoptosis plays a role in the mechanism of cell death caused by pdt based in zn-pc.
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